Jet injector



April 21, 1970 M. B. BURGESS JET INJECTOR 3 Sheets-Sheet 1 Original Filed Mayfi, 1965 INVENTOR. MURRAY B. BURGESS" m 1. f m mwws ATTORNEY April 21, 1970 M. B. BURGESS JET INJECTOR 3 Sheets-Sheet 2 Original Filed May 6, 1965 FIG. 2

JET INJECTOR i 3 Sheets-Sheet 5 Original Filed May 6, 1965 FIG. 4

FIG.3

United States Patent 3,507,276 JET INJECTOR Murray B. Burgess, 915 Harrison Drive, Huntington, N.Y. 11743; Catherine M. Burgess, administratrix of said Murray B. Burgess, deceased Continuation of application Ser. No. 453,580, May 6, 1965. This application Aug. 28, 1968, Ser. No. 764,009 Int. Cl. A61m 5/30 US. Cl. 128-173 8 Claims ABSTRACT OF THE DISCLOSURE The hypodermic jet injector (FIG. 1) has a jet orifice 12 to which fluid is applied under pressure through a one-way valve 14 from a cylinder 18. The cylinder 18 is charged through a central opening 100 and a one-way valve 22 in piston from a canula 24 carried by the piston. A single lever 26 cocks the firing spring 28 (FIG. 2) and then trips the latch 30 (FIG. 3) upon further movement to fire the device by releasing piston 20 to provide the injection.

This is a continuation of application Ser. No. 453,580 filed May 6, 1965, now abandoned.

This invention relates to improved jet injection apparatus which is particularly adapted as a hypodermic jet injector for the injection of medical liquids through the outer skin surface of either humans or animals, without the use of a hypodermic needle.

In recent years, there have been introduced a number of hypodermic jet injector devices for the injection of small amounts of medical liquids such as vaccines, medicines, anesthetics, and the like, without the use of a needle. The most obvious advantage of these devices is that they avoid the usual requirement of a newly sterilized needle for every injection because the patients skin is penetrated only by the droplets of the liquid to be injected.

The jet injector apparatus of the present invention may be employed with an infinite variety of different medicines, vaccines, and anesthetics. For certain purposes, such as for opening shallow skin abcesses, the instrument may usefully employ sterilized water, or alcohol, or the like as the liquid to be injected from the instrument and injected into the skin of the patient. Throughout the present specification, all of these possible liquids to be injected may be simply referred to as liquid or medical liquid, and these terms will be understood to en compass any of the liquids to be injected.

There is a tremendous need for small, portable, handoperated jet injectors, even though such injectors are necessarily generally limited to low volume injections in the order of one-tenth to one-half cubic centimeters of liquid. Such a low volume injection is nevertheless very useful for various purposes such as inoculations, injection of high-concentration medications, and the injection of small volumes of local anesthetic. This is useful for minor dental, or other surgery, or to anesthetize to permit the insertion of a larger needle painlessly for higher volume injections, or for making blood donations.

Both in the small portable sizes, and in the large nonportable sizes, various common problems are encountered. One of the most serious problems is that of air entrapped within the instrument together with the liquid to be injected. Such entrapped air reduces the efficiency of the injection operation because the air acts as a pressure cushion to reduce the high peak pressure and to thus reduce the velocity of the liquid stream. If there is more than a very nominal amount of air present with the liquid in the instrument, the cushioning effect causes it to fail to operate. Furthermore, when the instrument does operate in what appears to be a proper manner, the reduction in efficiency due to the presence of the air raises an immediate uncertainty as to the size of the effective dosage of the injected liquid.

Another problem which is encountered when air becomes mixed with the injection liquid is that a certain amount of the air will be injected together with the liquid into the skin of the patient, and this causes undesired discomfort and distress to the patient, and may cause an embolism.

Accordingly, it is an important object of the present invention to provide an improved jet injector apparatus which substantially precent the introduction of air into the presence of the liquid to be injected.

Another problem with prior jet injections has been the risk of contamination to the reservoir of liquid by the introduction of atmospheric air into the instrument to displace portions of liquid already ejected. The air within medical treatment rooms is often badly contaminated with various infectious substances.

Accordingly, it is another important object of the present invention to avoid and prevent virtually all contact of atmospheric air with the reservoir of liquid.

One of the most common problems with prior jet injectors has been the difficulty in causing the liquid to enter the ejection chamber. This has been variously described as difiiculty in loading, charging, or priming. In many such instruments, gravity is heavily relied upon to enhance the charging or priming action, and in some instances, gravity is completely relied upon for this purpose. Where gravity is an essential force in the priming operation, the instrument must be carefully held in a particular attitude for the gravity priming, and the force of gravity is generally inadequate to provide for reliable priming without a long wait for the liquid to percolate into the ejection chamber.

Accordingly, it is another important object of the present invention to provide an improved jet injector apparatus which provides positive pressure priming without any reliance upon gravity, and without an requirement for a substantial waiting period or a special attitude of the instrument for priming.

Another problem encountered With prior jet injectors is the risk of contamination of the parts with which the liquid comes in contact during a reloading operation in which new liquid is placed in the apparatus.

Accordingly, it is another important object of the present invention to provide an improved jet injector apparatus which minimizes the surface areas of the instrument which are to be in contact with the liquid.

Another object of the invention is to provide an improved jet injector apparatus which prevents contamination of any parts which come in contact with the liquid during reloading.

Another object of the invention is to provide a jet injector apparatus which is essentially self-cleansing and which provides a minimum surface area to be contacted by the liquid so that it is possible to change the nature of the liquid to be injected by the apparatus merely by changing the contents of the liquid reservoir of the instrument and purging the remanents of the prior liquid by operating the instrument several times with the new liquid.

While the volume of liquid which can be injected by a portable jet injector is necessarily rather limited, many common medicines can be produced and packaged in much higher concentrations than those in which they are usually available, and in such high concentrations, with an accurate means of injection, adequate medication can be provided with very low volume injections.

Accordingly, it is another important object of the present invention to provide a portable jet injector for low volume injections which is extremely accurate in its operation so as to permit the use of low volume, high concentration medicines.

In accordance with the invention, in addition to the above objects, the apparatus of the present invention provides various important advantages, including simplicity of construction, ease and simplicity of operation, and ease and economy in repair and parts replacement.

Furthermore, another important advantage of the invention is in the provision, in one preferred form thereof, of means for accommodating a standard ampule or cartridge of injection liquid, the cartridge itself serving as the reservoir of injection liquid within the instrument.

Further objects and advantages of the invention will be apparent from the following specification and the accompanying drawings.

In carrying out the present invention in one preferred form thereof, there is provided an improved hypodermic jet injector apparatus having a housing member with a jet orifice therein and a first one-way valve operable to provide flow of the liquid to be injected to the orifice. A reciprocable member is associated with the housing member and includes a second one-way valve. One of the members forms a cylinder and the other one of the members forms a cooperating piston within the cylinder to define, a variable volume chamber of restricted cross section between the first and the second valves, the second valve being arranged to provide free flow of liquid to ,the chamber. The reciprocable member includes an inlet passage and connections for a supply container of the liquid for conveying the liquid to the second valve. A quick release compression device is provided to impart a fast and powerful movement to the reciprocable member in the direction to reduce the volume of the chamber to cause ejection of the liquid from the chamber through the orifice with sufficient force to penetrate the skin of the patient.

In the accompanying drawings:

FIG. 1 is a side view, partially in section, of a preferred embodiment of the invention.

FIG. 2 is a similar view showing the apparatus of FIG. 1 in a cocked condition ready for an injection operation.

FIG. 3 is a partial detail view showing the operation of the latch to release and fire the jet injector of FIG. 1.

And FIG. 4 is an enlarged detail view of the second valve .and the associated portions of the apparatus.

Referring in more detail to FIG. 1, there is shown a housing member having a jet orifice at 12, a one-way valve 14 arranged to provide liquid flow through the orifice. A reciprocable member 16 defines, together with the "housing member 10, a variable volume chamber 18. The reciprocable member 16 includes a piston 20 which moves axially within a cylinder formed in the housing member 10 to accomplish the variation in the volume of the chamber 18. The reciprocable member 16 includes a one-way valve 22 which provides for movement of liquid into the chamber 18 from a liquid reservoir generally indicated at 24. The movable member 16 is retracted to enlarge the chamber 18 by clockwise rotation of a'lever 26. The resultant movement of the member 16 is in a direction towards the top of the drawing, as shown in FIG. 2. This upward movement of member 16 causes charging of the liquid from reservoir 24 through the one-way valve 22 into the chamber 18. The upward movement also causes compression of a powerful spring 28. When the reciprocable member 16 is later released, the energy stored in the spring 28 causes a rapid and powerful downward movement of the member 16, closing the one-way valve 22, rapidly reducing the volume of chamber 18, opening the one-way valve 14, and causing the jet ejection of the liquid through the orifice 12.

FIG. 2 illustrates the retracted or cocked position of the reciprocable member 16, in which the lever 26 has been rotated to retract the piston 20, and to compress the spring 28. In this cocked position, the movable member is engaged and retained by a latch member 30 until the jet injection operation is required.

FIG. 3 illustrates how further clock-wise rotation of the lever 26 releases the latch 30 to trigger the jet injection operation.

The following is a more detailed decription of the structure and operation of the invention, as shown in the embodiment of FIG. 1.

The housing member 10 includes a cylinder 32. A nose piece 34 is attached to the cylinder 32 by means of a collar 36, the collar 36 having a threaded attachment to the cylinder 32. Threadedly fastened into the nose piece 34, there is a nozzle tip 38. At the bottom of the threaded opening of the nose piece 34, which receives the nozzle tip 38, there is positioned an orifice plate 40. The orifice plate 40 may conveniently consist of a small disk of stainless steel which is about two-hundredths of an inch thick, with the orifice 12 formed in the center as a hole approximately six-thousandths of an inch in diameter. The orifice plate 40 is firmly held in place by securely tightening the nozzle tip 38. However, it may be easily removed forcleaning or replacement by simply unscrewing the nozzle tip 38. The orifice plate 40 is preferably made very thin, as described, in order to prevent clogging, and in order to make cleaning easier, and also to generate a very small thin stream of ejected liquid, with a minimum of dispersion.

The tip 38 and the orifice plate 40 are conveniently arranged at an angle with respect to the remainder of the body of the instrument as a convenience in administering injections in confined locations. For instance, for dental use, the instrument may be inserted into the mouth of the patient, and the injection easily made in the angular direction into the gum tissue of the patient. The angle of the injection about the axis of the instrument can be simply changed by rotating the entire instrument, or by loosening the collar 36 and rotating the nose piece 34 to the desired angle. If desired, a short piece of rubber tubing may be fitted over the nozzle 38 to serve as a nonmetallic contact tip for engagement with the skin surface of the patient. This serves as a spacing device to con trol the spacing between the orifice and the skin surface. It is important, for satisfactory and reproducable operation, that the orifice must be within a rather short uniform space from the skin of the patient in order that the jet stream will have sufiicient power and momentum to penetrate in a uniform volume.

Within the bore of the nose piece 34, there may be positioned one or more strainer screens 42 which are preferably from 200 to 400 mesh. These screens provide the useful function of straining the liquid so as to help prevent any obstruction of the orifice 12. The screens 42 are held in place by a conical spring 44, which is also the operating spring for the one-way valve 14. The valve 14 consists simply of a member having a spherical surface which seats into a suitable restriction of the bore of the cylinder 32. In order to improve the seal afforded by the one-way valve 14, the portion containing the spherical surface may be composed of gum rubber having a durometer hardness in the order of fifty. In order to improve the pressure holding capabilities between the piston 20 and the inner surface of the cylinder 32, a rubber O ring 46 may be provided, which is held in assembled relationship within the cylinder member 32 by means of a retainer plug 48 threadedly fastened into a suitable depression in the cylinder 32. Both of the rubber parts 46 and 14 are preferably coated with materials having a pH factor to match the pH factor anticipated for the liquids to be injected. Furthermore, these parts may be composed of rubber or rubber-like materials which are capable of withstanding sterilization temperatures. Other materials such as nylon or Teflon (DuPont trademark for polytetrafiuroethylene) may also be used for the ball valve.

The remainder of the housing of the apparatus consists of tube 50, which is threadedly fastened to cylinder 32, top tube 52, which is threadedly fastened to tube 50, and clevis block 54, which is threadedly fastened to the tube 52. The clevis block 54 includes pivot pins 56 and 58 for pivotally supporting the lever 26 and the latch 30.

The reciprocable member 16 includes the one-way valve 22, of which the most essential component is a check plate 60 positioned within a chamber formed within the piston member 20. The upper wall of the chamber for the valve 22 is formed by a canula member 62 which is maintained in assembled relationship within the piston member 20 by means of screw threads which engage interior threads of the cylinder member 20. The structure and operation of the valve 22 is described in greater detail below in connection with the enlarged detail view of FIG. 4.

The cartridge tube 64, which is mounted to cylinder 20 by the same screw threads which mount the canula, provides a chamber for the reservoir of liquid to be injected. Tube 64 includes a flange 65 engaging spring 28. Attached to the upper end of the cartridge tube 64 there is a spring cap 66. The enclosure or chamber formed by the spring cap 66, the cartridge tube 64, and the canula 62 is preferably proportioned and arranged to receive a standard cartridge of medical liquid to be injected. Thus, the reservoir 24 is illustrated as consisting of such a standard cartridge. -For instance, the cartridge may be the standard 1.8 cubic centimeter size having outer dimensions of approximately five-sixteenths of an inch by two and onehalf inches. A 2.2 cubic centimeter cartridge of the same diameter, and slightly greater length may also be accommodated. The reservoir cartridge 24 is described in detail here as a part of the preferred structure of the present invention. However, it will be understood that the cartridge itself does not comprise a novel part of the present invnetion since the cartridge is a standard and wellknown package for medical liquids. The reservoir cartridge 24 preferably consists of a glass tube 68 having a slidable rubber stopper 70 at its upper end, and a rubber membrane closure 72 at its lower end. The canula 62 includes a hollow hypodermic tube needle portion having a tip 74 which extends into the cartridge chamber so as to pierce the membrane 72 when the cartridge 24 is inserted fully. The membrane member 72 may take any one of a number of standard forms provided there is a thin wall at the central portion thereof which is easily penetrated by the tip 74. Thus, it is quite apparent that the canula 62 provides communication with the reservoir cartridge 24, for the flow of liquid through the valve 22 and into the chamber 18.

The entire space within the cartridge 24 is preferably filled with liquid. As the cartridge 24 is emptied, all of the displacement of liquid is accommodated for by downward movement of the slidable rubber stopper 70. Preferably, this movement is assured by the provision of a light spring 76 having a tip 78 which is arranged to engage the rubber stopper 70. The force of spring 76 is suflicient only to overcome a part of the static friction of the slidable rubber stopper 70' to insure that, as liquid is removed from the reservoir cartridge 24 into the chamber 18, the slidable stopper 70 does the complete job of displacing the liquid space. Thus, no atmospheric air is permitted to enter the portion of the cartridge which continues to contain liquid, nad the liquid therefore is not subjected to possible contamination from such atmospheric air.

Mounted over the lever pin 56, there is a latch spring 80 having double arms at 82 which straddle and engage the rotatable latch member 30 to bias it for rotation in a clockwise direction. The spring 80 also includes arms 84 which straddle and bias the lever 26 in a clockwise direction.

The latch 30 is provided with two engagement fingers 86. The latch is normally held in a disengaged position with the ends of the fingers 86 resting against the outer surface of a radial flange portion 88 of the spring cap 66. The lever 26 has a lost motion pivotal connection with the lever pin 56 by reason of the slotted lever pin opening 90. When the lever 26 is raised to the extended position shown in FIG. 1, it is biased downwardly by spring 80, at the pivot pin 56, so that the finger portion 92 of the lever engages the bottom of the flange portion 88 of the spring cap 66. Downward clockwise rotation of the lever 26 then raises the spring cap 66, and the entire reciprocable member 16, including the piston 20'. If this movement is continued far enough, the spring cap flange 88 is raised beyond the latch fingers 86, so that the latch fingers 86 slide under the flange 88 and retain the reciprocable member in the raised or cocked position.

FIG. 2 illustrates the cocked condition of the device. During the upward movement, the chamber 18 is enlarged by the upward travel of the piston 20, the valve 22 is opened by a slight downward movement of valve plate 60, and the valve 14 remains closed. Liquid is thereby pumped from the reservoir cartridge 24 through the canula 62 and the valve 22 into the chamber 18. This movement of liquid into the chamber 18 is accomplished largely by atmospheric pressure, as otherwise there would be essentially a partial vacuum within the chamber 18 as it is enlarged. This charging of chamber 18 is enhanced by the spring 76, which helps to move the slidable rubber stopper 70 downwardly, as indicated in FIG. 2.

When the device is to be tripped or fired, the lever 26 is given a further rotational motion in the clockwise direction. The lever 26 then engages a fulcrum pivot point 94 of the clevis block 54. This causes the lever to rotate about the pivot point 94 through the lost motion provided by the slotted connection 90 with the pin 56. As this motion continues, the lever finger 92 engages the latch 30 between the latch fingers 86. This imparts a counter-clockwise rotation to the latch 30.

FIG. 3 shows the operation, disengaging the latch and allowing the entire movable member, including the piston 20 to move rapidly downward under the force of the spring 28. During this downward travel of the reciprocable member 16, the one way valve 22 closes, and the one way valve 14 opens, so that the liquid previously contained within chamber 18 is forcibly ejected with considerable force and speed through the screen 42 and the orifice 12.

There is a measurable volume within the housing between the valve 14 and the orifice 12 which must be filled with liquid before an effective injection operation is possible, the volume of this space is preferably somewhat less than a single injection charge. Accordingly, it is possible to fill this space with liquid by simply operating the device through one or more injection cycles at the beginning of a particular period for use, before actual injections are commenced. This also serves to purge all air from chamber 18. Another convenient method for priming the injector and purging the air from the system is to insert a rod at the top of the instrument through center opening 110, and through members 76 and 78, to engage the slidable stopper 70. Pressure exerted by the rod upon the stopper 70 causes downward movement of the stopper 70, and movement of liquid through both one-way valves 22 and 14 until a small amount of liquid is seen to be emitted from the nozzle 38.

FIG. 4 is an enlarged detail drawing showing the construction of the one-way valve 22. As previously mentioned, the most essential element of valve 22 is a check plate 60 which is housed in the chamber defined by the inner surfaces of the piston 20 and the canula 62. The sides of the chamber adjacent to the outer edges of the check plate 60 conform in shape with the check plate 60 so as to provide a slidable fit therewith. Conveniently, both the plate and the chamber are circular. The check plate 60 is provided with one or more axially aligned through holes 96 which are radially displaced from the center of plate 60 so that they are not in alignment with the center hole of the canula 62. Thus, when the plate 60 floats upwardly within its chamber and snugly engages with the lower surface of the canula 62, both the through holes 96 of the plate, and the central opening of the canula 62, are effectively closed. This is the condition which exists as the volume of chamber 18 is reduced the firing of the injector. At the bottom of the valve chamber, there is a portion of reduced diameter at 98. The diameter of this portion is less than the outer diameter of the check plate 60, but is great enough to form a communication with the through holes 96. Thus, it provides a free passage through the central opening 100 in the piston 20. Therefore, when the check plate 60 floats downwardly within its chamber, the center opening of the canula is uncovered and liquid can flow downwardly, through the chamber and through the openings 96, and then through the central opening 100 of the piston 20. The central opening 100 is considered to be a part of the chamber 18.

One of the outstanding features of the present invention is the positive filling operation provided by the cooperation of the two valves 14 and 22. Thus, whenever the chamber 18 is enlarged by upward movement of piston 20, valve 22 opens and the liquid is provided in a continuous fiow through the valve 22 and the central passage 100 into the chamber 18. During this operation, the increased displacement within the chamber 18 must be satisfied entirely through valve 22 because valve 14 is automatically retained in the closed position, the slightly reduced pressure within the chamber 18 causing the valve 14 to close securely. Upon the injection operation, when the piston 16 descends, the valve 22 closes and the valve 14 opens to provide for one way flow of liquid out through the orifice 12. It is apparent that the valves 14 and 22 cooperate with the cylinder of the housing and the piston 20 to provide a double action pump operation. The continuous action of the valves, and particularly of the action of valve 22, during the upward travel of the piston 20, which provides continuous access of liquid to the chamber 18 assures that there is a complete filling of the chamber with the liquid and noopportunity for any atmospheric air to enter the chamber 18. As previously mentioned above, the entry of air into the liquid system is very undesirable for a number of reasons.

The tube 50 of the housing 10, and the cartridge tube 64 of the reciprocable member 16 are respectively provided with window openings 102 and 104. These windows are preferably provided on both sides of the tubes 50 and 64 and thus they provide a visual indication when the cartridge 24 is almost emptied. This will be clearly indicated by the approach of the slidable stopper 70 into the window area. Providing the windows on both sides of the tubes promotes full visibility of the stopper 70 through the glass walls of the cartridge 68 because back lighting is thus provided from the side of the cartridge opposite to the side which is viewed.

Since the reciprocable member 16 is freely rotatable within the housing 10, the windows 102 and 104 will not always be perfectly aligned. However, they can be easily aligned with one another by manual rotation of the reciprocable member by engagement of the fingers of the operator with the upper tip of the spring cap 66.

Sterilization of the jet injector of this invention can be easily accomplished by simply placing the entire injector structure into the autoclave. However, the used reservoir cartridge 24 should be first removed from the interior of the device. This can be accomplished very simply by unscrewing the spring cap 66 where it is attached to the upper end of the cartridge tube 64. The outer periphery of the upper tip of the spring cap 66 is knurled to give the fingers at good purchase on this part. The cartridge tube 64 can be held against rotation to permit the removal of the spring cap 66 by inserting the fingers of the other hand through the windows 102 and 104. However, the constraint offered by spring 28 is usually sufficient to prevent rotation of cartridge tube 64 during removal of cap 66. After removing the spring cap 66, the spring 76 and the spring tip 78 easily slide out of the cartridge tube 64 together with the reservoir cartridge 24. The reservoir cartridge 24 is easily disengaged from the needle 74 of the canula 62 by manipulation through the windows 102 and 104. A new cartridge can then be inserted through the upper end of the cartridge tube 64, and forced down over the canula needle tip 74 by manipulation through the windows 102 and 104. The spring 76, the spring tip 78, and the spring cap 66 are then reassembled and tightened in place. If desired, to assist and maintain the assembly of the cartridge tube 64 over the tip 74, a spring member (not shown) may be arranged within the cartridge tube 64 and between the upper edge of the glass tube portion of the cartridge 68 and the lower edge portion of the spring cap 66, and surrounding the spring 76.

It is one of the important features and advantages of the structure that a used reservoir cartridge 24 can be removed, and a full reservoir cartridge 24 can be inserted, without exposing any of the parts of the injector apparatus which must be sterile to any serious possibility of contamination. Thus, it is possible to use the jet injector for a considerable number of injections, employing a succession of dilferent cartridges, without the necessity for resterilization. Furthermore, it is even possible to change from one injection liquid to another, provided such liquids are not seriously incocompatible, by simply loading the new reservoir cartridge 24 and purging the apparatus by operating it several times with the new cartridge be fore beginning injections.

It is to be understood that each of the cartridges 24 holds a sufiicient volume of liquid for a number of jet injections. With the proportions illustrated, in the order of twenty injections may be made from a single liquid reservoir 24 of 1.8 cc. capacity.

A practical diameter for the piston 20 in the embodiment illustrated, is approximately 0.15 inch, and the travel of the piston 20 may be in the order of one-quarter of an inch. This provides a displacement of about 0.08 cc. The other dimensions of the apparatus, which have not been particularly specified, are preferably in proportion as illustrated in the drawings.

While the entire device is constructed so that it can withstand sterilization heating, it is preferable to sterilize only those parts which absolutely must be sterile and to avoid sterilization heating of certain parts such as the springs 28 and 76. For the purpose of this limited sterilization, the outer housing can be conveniently disassembled at the connection between tube 50 and upper tube 52, and all of the parts of the housing shown below the disassembly point may then be sterilized. With the movable member 16, the disassembly preferably is at the connection between the cartridge tube 64 and the piston 20, the entire assembly of the movable members shown below this point being sterilized. Except for the ball valve 14, and the O ring 46, the entire instrument is composed of metal. This statement is made with the understanding that the cartridge 24 is not considered to be a part of the instrument. Generally, the preferred material for all of the metal parts, including springs 28 and 76, is stainless steel so that the moisture conditions during sterilization of the entire instrument do not cause any problem.

The pressures required within the chamber 18 during an injection operation are appreciable. Generally, with the specific dimensions given by way of example above, the pressures should be generally in excess of 450 pounds per square inch. The actual theoretical design pressures for the embodiment shown are in the range from about 500 to about 650 pounds per square inch. Higher pressures in the order of 750 pounds per square inch, or more, may be required for difficult injection conditions.

The preferred arrangement of the liquid reservoir 24 is as shown in the drawings. It is one of the important advantages of the present invention that it is particularly adapted to accommodate standard sized medical liquid cartridges. However, the structure is also adapted, without substantial change, to operate with a rather large. exterior reservoir of medical liquid. For this purpose, the reservoir cartridge 24, and preferably the spring 76 and the spring tip 78 are removed. A small flexible tubing leading from a large medical liquid reservoir bottle is threaded through the central opening 110 in the spring cap 66. The end of this tubing is then fitted over the tip 74 of the canula 62. Preferably, such an external reservoir bottle may be of a collapsible plastic type so that atmospheric air need not be introduced into the bottle to make up for the displacement of liquid from the bottle as it is emptied.

While the jet injector, as it is disclosed in the accompanying drawings, is basically a single dosage charge volume device, it is apparent that the injection dosage volume can be very simply increased by increasing the length of the cylinder 32, and correspondingly increasing the length of the piston 20, and by designing the lever 26 and the associated latching arrangements to provide for greater piston travel. One such arrangement is to provide a number of spaced flanges on the spring cap 66 corresponding to flange 88, and arranged in such a Way that repeated up and down motions of the lever 26 will suecessively engage the dilferent flanges and thereby give the movable member an additional cocking displacement for each clockwise cocking operation of the lever 26. In this manner, the device may be set to deliver a single charge, a double charge, or an additional number of charges for which the device is designed. Minor changes and adjustments in the charge volume may be made by cutting away the lower surface of the flange 65 of the cartridge tube 64, or the lower surface of the flange 88 of the spring cap 66. Reducing the flange 65 increases the stroke and the displacement, and reducing the flange 88 decreases the displacement by decreasing the travel of the movable member to the point where latch 30 engages the flange 88. A very simple adjustment of the stroke, and the displacement, may be accomplished by unscrewing the cap 66 at its screw threaded fastening to the cartridge tube 64. This is equivalent to cutting away the lower surface of the flange 88. The amount of unscrewing rotation of the cap 66 will determine the amount of reduction of volume of the ejection. For purposes of absorbing the mechanical shock at the end of the stroke of the movable member 16, a washer of a non-metallic material such as nylon may be inserted beneath the flange 65, if desired. This alternative is not illustrated. A washer of only one thirty-second of an inch in thickness has been found to accomplish this purpose very well. It is obvious that the presence of the washer changes displcaement volume, and minor adjustments of the displacement volume may be accomplished by employing washers of different thickness.

Various modifications may be made in the latching structure. For instance, instead of employing the latch member 30, a latch may be provided for holding the lever 26 in the cocked position. This arrangement can take the form of a latch arm similar in appearance to the spring arm 84, but which is pivoted closer to the center of the casing than the lever pivot 56. This latch arm is arranged to drop into a notch on the outer surface of lever 26.

While arrangements for manual cocking of the instrument have been illustrated and described in connection with the preferred embodiment, it is quite apparent that other structures may be employed for cocking the instrument by means of powered devices such as electric motors. One such arangement can employ a motor-operated screw jack for raising the movable member to a point where the latch 30 can engage it. However, such power arrangements 10 increase the weight and bulk of the device and thereby reduce its portability. Accordingly, such a power operated version of the invention is not preferred.

It is believed to be apparent from the drawings and the above description that all of the objects and advantages of the invention have been achieved.

While this invention has been shown and described in connection with a single preferred embodiment, it is apparent that various changes and modifications, in addition to those mentioned above, may be made by those who are skilled in the art without departing from the basic features of the invention. Accordingly, it is the intention of the applicant to protect all variations and modifications within the true spirit and valid scope of this invention.

What is claimed is:

1. A hypodermic jet injector comprising a housing member defining a jet orifice arranged in a blunt terminal portion thereof, a first one-Way valve formed within said housing member and operable to provide flow of the liquid to be injected to said orifice and to prevent backward fiow through said valve, a member mounted for reciprocable movement with respect to said housing member, one of said members forming a cylinder and the other one of said members forming a cooperating piston within said cylinder to define a variable volume chamber of restricted cross section, one of said members including a second one-way valve communicating with said chamber and arranged to provide free flow of liquid to said chamber, said last-named member further defining an inlet passage for conveying liquid through said second valve to said chamber and including connections for a supply container of the liquid, said last-named member also defining a cartridge chamber for engaging and holding a pre-packed liquid cartridge of the type having a pierceable seal at the outlet end and a slidable rubber stopper at the opposite end and serving as the liquid supply container, said connections for the supply container including a canula with a hollow ti'p extending into the cartridge chamber adjacent to said second valve for piercing the seal at the outlet end of the cartridge, and a quick-release compression device comprising a spring engaged between said members and restrained by a latch supported by said housing member and engageable with said reciprocable member, a cocking lever pivotally mounted on said housing member and engaging said reciprocable member for moving said reciprocable member against the pressure of said spring to enlarge said chamber, said compression device being operable upon release of said latch to impart a fast and powerful movement to said reciprocable member in the direction to reduce the volume of said chamber to cause ejection of liquid from said chamber through said orifice with sutficient force to penetrate the skin of the patient.

2. A hypodermic jet injector comprising a housing member defining a jet orifice arranged in a blunt terminal portion thereof, a first one-Way valve formed within said housing member and operable to provide flow of the liquid to be injected to said orifice and to prevent backward flow through said valve, a member mounted for reciprocable movement with respect to said housing member, said reciprocable member having formed therein a second one-way valve, one of said members forming a cylinder and the other one of said members forming a cooperating piston within said cylinder to define a variable volume chamber of restricted cross section between said valves, said second one-way valve being arranged to provide free flow of liquid to said chamber, said reciprocable member further defining an inlet pas sage for conveying liquid through said second valve to said chamber and including connections for a supply container of the liquid, a quick-release compression device comprising a spring engaged between said members and restrained by a latch supported by said housing member and engageable with said reciprocable member, said compression device being operable upon release of said latch to impart a fast and powerful movement to said reciprocable member in the direction to reduce the volume of said chamber to cause ejection of liquid from said chamber through said orifice with sufficient force to penetrate the skin of the patient, said reciprocable member defining a cartridge chamber for engaging and holding a pre-packed liquid cartridge of the type having a pierceable seal at the outlet end and a slideable rubber stopper at the opposite end and serving as the liquid supply container, said connections for the supply container including a canula with a hollow tip extending into the cartridge chamber adjacent to said second valve for piercing the seal at the outlet end of the cartridge.

, 3. A jet injector as claimed in claim 2 wherein said reciprocable member is operable in cooperation with said valves to cause the charging of said variable volume chamber as said chamber volume is increased by outward movement of said reciprocable member, said charging being carried out under positive atmospheric pressure through said second one-way valve to fill the enlarged volume of said chamber.

4. A jet injector as in claim 2 in which a biasing spring is positioned within said reciprocable member for engagement with the rubber stopper of the liquid cartridge for biasing the stopper into the cartridge as the cartridge is emptied to thereby displace the liquid without introducing atmospheric air to the liquid within the cartridge.

5. A jet injector as claimed in claim 2 wherein said second valve comprises an axially reciprocable plate floating within a chamber defined within sad piston member conforming to the outer periphery of said plate and having an axial dimension greater than the thickness of said plate, said plate having at least one axial opening therethrough, and the wall of said chamber on one side of said plate being completely closed in the radial position opposite to said aperture to thereby close said valve whenever said plate engages said closed chamber wall, the opposite wall of said chamber being relieved in the radial position opposite to said aperture to thereby open said valve whenever said plate engages said opposite wall.

6. A hypodermic jet injector comprising a housing member defining a jet orifice arranged in a blunt terminal portion thereof, a first one-way valve formed within said housing member and operable to provide flow of the liquid to be injected to said orifice and to prevent backward flow through said valve, a member mounted for reciprocable movement with respect to said housing member, said reciprocable member having formed therein a second one-Way valve, one of said members forming a cylinder and the other one of said members forming a cooperating piston within said cylinder to define a variable volume chamber of restricted cross section between said valves, said second one-way valve being arranged to provide free flow of liquid to said chamber, said reciprocable member further defining an inlet passage for conveying liquid through said second valve to said chamber and including connections for a supply container of the liquid, a quick-release compression device comprising a spring engaged between said members and restrained by a latch supported by said housing member and engageable with said reciprocable member, said compression device being operable upon release of said latch to impart a fast and powerful movement to said reciprocable member in the direction to reduce the volume of said chamber to cause ejection of liquid from said chamber through said orifice with sufiicient force to penetrate the skin of the patient, a pivoted cocking lever for moving said reciprocable member against the pressure of said spring to enlarge said chamber, said latch being engageable with said reciprocable member for retaining said reciprocable member in the cocked position, said lever having a lost motion pivotal connection with said hous ing member and being movable at said lost motion connection to engage and release said latch upon continued excursion of said lever after completion of the cocking operation.

7. A hypodermic jet injector comprising a housing member defining a jet orifice arranged in a blunt terminal portion thereof, a first one-way valve formed within said housing member and operable to provide flow of the liquid to be injected to said orifice and to prevent backward flow through said valve, a member mounted for reciprocable movement with respect to said housing member, said reciprocable member having formed therein a second one-way valve, said housing member defining a cylinder and said reciprocable member including a portion forming a cooperating piston within said cylinder to define a variable volume chamber of restricted cross section between said valves, said second one-way valve being arranged to provide free flow of liquid to said chamber, said reciprocable member further defining an inlet passage for conveying liquid through said second valve to said chamber and including connections for a supply container of the liquid, a quick-release compression device comprising a spring engaged between said members and restrained by a latch supported by said housing member and engageable with said reciprocable member, said compression device being operable upon release of said latch to impart a fast and powerful movement to said reciprocable member in the direction to reduce the volume of said chamber to cause ejection of liquid from said chamber through said orifice with sufficient force to penetrate the skin of the patient, said piston and said cooperating cylinder having a small cross section to provide a high force per unit area from said quick-release compression device, said second oneway valve being axially displaced from said piston portion of said reciprocable member in a portion thereof having a larger cross section than said piston portion, said piston portion including a central bore extending from said second one-way valve and forming part of said chamber.

8. A jet injector comprising a cylinder member and a piston member arranged for cooperative engagement to define a variable volume chamber, each of said members including a one-way valve communicating with said chamber, said cylinder member including a jet orifice, and the valve of said cylinder member being arranged to provide flow from said chamber to said orifice, the valve of said piston member being arranged to provide flow into said chamber, said piston member valve comprising an axially reciprocable plate floating within a chamber conforming to the outer periphery of said plate and having an axial dimension greater than the thickness of said plate, said plate having at least one axial opening therethrough, and the wall of said chamber on one side of said plate being completely closed in the radial position opposite to said aperture to thereby close said valve whenever said plate engages said closed chamber wall, said piston member defining a cartridge chamber for engaging and holding a prepacked liquid cartridge of the type having a pierceable seal at the outlet end and a slidable rubber stopper at the opposite end to serve as the liquid supply container, a connection for the supply con tainer including a canula with a hollow tip extending into the cartridge chamber adjacent to said second valve for piercing the seal at the outlet end of the cartridge, a. biasing spring positioned within said piston member for engagement with the rubber stopper'of the liquid cartridge for biasing the stopper into the cartridge as the cartridge is emptied to thereby displace the liquid without introducing atmospheric air to the liquid within the cartridge, said piston member being operable in cooperation with said valves to cause the charging of said variable volume chamber as said chamber volume is increased by outward movement of said piston member, said charging being carried out under positive atmospheric pressure through said second one-way valve to fill the enlarged volume of said chamber, a spring connected between said cylinder member and said piston member for biasing 2,653,604 9/ 1953 Hein.

said piston member in the direction to reduce the volume 2,816,543 12/ 1957 Venditty et al. of said chamber, a pivoted cocking lever for moving said 2,821,195 1/ 1958 McLintock.

piston member against the pressure of said spring to en- 2,902,994 9/1959 Scherer large said chamber, a latch member pivotally connected 5 2,921,582 1/ 1960 Sadd to said housing member and engageable with said piston 2,948,223 8/1960 Mashinter.

member for retaining said piston member in the cocked 3,113,523 12/1963 Woodward et 31. position, said lever having a lost motion pivotal connec- 3,129,708 4/1964 Krantz tion with said cylinder member and being movable at 3,292,622 12/ 1966 Banker.

said lost motion connection to engage and release said 10 3,335,722 8/ 1967 LoWry et a1. latch member upon continued excursion of said lever 2,669,230 2/ 1954 Smoot.

after completion of the cocking operation. 3,057,349 10/1962 Ismach.

References Cited UNITED STATES PATENTS RICHARD A. GAUDET, Primary Examiner 15 K. L. HOWELL, Assistant Examiner 1,363,128 12/1920 Kitoaka. 1,655,909 1/1928 Laurent. 128 218 2,643,655 6/1953 McKay. 

